The Problem

Osteolysis of the distal clavicle is considered an overuse injury resulting from repeated microfracture and attempted remodeling. Stress on the end of the clavicle causes further degeneration of the cartilage in the acromioclavicular joint. While commonly associated with weightlifters, osteolysis can also occur in patients performing repetitive overhead lifting and carrying. Conservative management includes activity modification, nonsteroidal medications, and corticosteroid injections. Operative treatment is indicated in patients failing conservative management and consists of a distal clavicle resection.

Clinical Presentation

Patients report aching pain in the acromioclavicular joint with repetitive activity. Positions that place the elbow posterior to the body, cross arm adduction maneuvers, and even overhead motions exacerbate the symptoms. With progression of the osteolysis, patients report sharp pain during activity that may continue as a deep ache during the subsequent 24 hours.

Diagnostic Workup

Patients will have no limitations in regard to motion and will not have shoulder instability. The acromioclavicular joint will be tender on palpation and patients will experience pain with passive adduction and resisted abduction, which will load the joint.

The differential diagnosis includes cervical spine pathology in addition to systemic disorders such as gout and rheumatoid arthritis that may cause symptoms similar to osteolysis. Impingement syndrome and rotator cuff disorders can typically be distinguished from osteolysis of the distal clavicle through physical examination.

While an anteroposterior view of the shoulder should be able to detect changes consistent with osteolysis, a Zanca view provides an unobstructed view of the acromioclavicular joint. The radiograph is taken with a fifteen degree cephalad tilt to avoid scapular overlap. Radiographs can be normal or can show signs of decreased mineralization and a decrease in distal clavicular width as compared to the opposite acromioclavicular joint.

MRI can be helpful in ruling out other shoulder pathology. However, typical findings with osteolysis of the distal clavicle include increased signal on T2 fluid sensitive sequences.

Acromioclavicular joint injections can be both diagnostic and therapeutic. Relief from symptoms can be temporary or permanent depending on the patient's activity and the extent of disease. The injection provides information regarding the success of surgical management if indicated.

Non–Operative Management

Modification of the activities causing symptoms, modalities, and nonsteroidal medications can relieve symptoms at the acromioclavicular joint. Altering the style of lifting weights or performing different types of exercises to work a given muscle group can be effective in patients who desire to continue their normal activities. Nonsteroidal medication can decrease synovitis and inflammation in the joint while modalities such as routine icing after activity can decrease symptom severity. A corticosteroid injection may also provide temporary or long term relief.

Indications for Surgery

Patients with examination and radiographic signs of osteolysis who have trialed conservative management with continued symptoms or those patients unwilling to modify their activity level with continued symptoms are indicated for surgery.

Surgical Technique

Surgery for osteolysis consists of a distal clavicle resection (Mumford procedure). Open and arthroscopic techniques have been described in the literature. The open technique has the advantage of being able to visualize the length of clavicle being resected. However, there is an increased morbidity involved with surgical dissection through the deltotrapezial fascia and superior acromioclavicular ligaments in addition to the potential for post-operative distal clavicle instability.

Arthroscopic distal clavicle excision is the recommended approach in cases of osteolysis of the distal clavicle. A subacromial approach allows evaluation of the rotator cuff and acromion while a direct superior approach avoids encroachment of the subacromial bursa. Removal of between 5-10mm of bone is recommended during surgical resection to eliminate symptoms.

A subacromial approach is recommended in the majority of cases. Patients should be placed in the lateral decubitus position on a bean bag with all bony prominences being padded. An axillary bump is utilized as well. The arm is placed in approximately 50-60 degrees of abduction and 10-15 degrees of forward flexion in 10-12lbs of balanced traction. It is helpful to delineate all landmarks on the skin with a marking pen including the acromioclavicular joint prior to starting the procedure. A standard posterior portal is made 2cm inferior to the posterolateral corner of the acromion through which the arthroscope is placed into the joint. A diagnostic arthroscopy is performed of the glenohumeral joint and the subacromial space. The anterior portal should be made keeping in mind its location in relationship to the acromioclavicular joint (Figure 1). If the portal is placed too far laterally (Figure 2), the angle of the burr toward the acromioclavicular joint makes arthroscopic resection more difficult.

Figure 1.

Left shoulder in the lateral decubitus position. AC joint keeping in mind angle of resection.

Figure 2.

Lateral portal makes resection more difficult.

Following the diagnostic arthroscopy, an electrocautery device should be used to demarcate the anterior and posterior borders of the acromioclavicular joint (Figure 3, Figure 4). The arthroscope can be switched from the posterior to the lateral portal to ensure that the posterior aspect of the clavicle is visualized. An arthroscopic burr (4 or 5mm round or barrel) can then be utilized to resect the distal clavicle through an anterior working portal (Figure 5). There are several ways to determine how much distal clavicle has been resected. Surgeons can utilize the burr as a guide or a calibrated probe can be placed through the lateral working portal (Figure 6). Additionally, a cannula placed in the anterior portal can also be used to measure the resection width (Figure 7). The lateral edge of the trapezoid ligament is located approximately 1cm from the end of the clavicle and resection should not proceed past this landmark. Additionally, the arthroscope should be placed in the anterior portal to visualize the resection to ensure that the superior clavicle does not angle toward the acromion indicating an uneven resection (Figure 8). Finally, a mini-fluoroscopy unit coming in from the head can also give information regarding the resection. Care should be taken to avoid an uneven resection or to disrupt the posterior and superior acromioclavicular ligaments which could lead to instability and pain. An arthroscopic shaver should remove bone debris prior to completion of the case.

Figure 3.

Anterior clavicular border.

Figure 4.

Posterior clavicular border.

Figure 5.

Distal clavicle excision.

Figure 6.

Calibrated probe through lateral portal.

Figure 7.

Cannula in anterior portal to assess resection.

Figure 8.

View of the AC joint through the anterior portal.

Pearls and Pitfalls of Technique

Pearls

Marking the skin prior to the procedure allows optimal placement of the anterior working portal.

Initial exposure of the clavicle with the use of a shaver and electrocautery is paramount to ensure a complete resection from anterior to posterior.

A cannula in the anterior portal can be utilized as a reproducible measuring device for resection width and the arthroscope placed into this cannula helps to assess the resection angle from inferior to superior.

Pitfalls

Poor visualization from portal placement or failure to properly visualize the distal clavicle can lead to underresection and continued symptoms. Conversely, overresection of greater than 1cm can lead to clavicular instability and pain.

Debridement of the posterior and superior acromioclavicular ligaments can lead to painful instability.

Failure to removed bone debris can lead to hetertopic ossification.

Potential Complications

Complications include lateral clavicle fracture, infection and postoperative hematoma. Continued pain can occur from underresection leading to continued impingement or overresection leading to painful instability.

Post–operative Rehabilitation

General guidelines following a distal clavicle excision include early motion and a progression to strengthening the rotator cuff musculature while avoiding cross arm adduction.

In the immediate post-operative period, patients are placed in a sling for comfort for the first few weeks. Physical therapy begins 2-3 days after surgery with the first month goal of regaining passive and active assisted range of motion and reducing pain and swelling. Cross arm adduction should be avoided in the first month after surgery. The second month goals include regaining active range of motion as tolerated, strengthening scapular stabilizers while avoiding active strengthening in cross arm adduction. At the 2.5-3 month postoperative period, goals include obtaining full strength in the rotator cuff. Return to functional activities occurs when patients have painless range of motion and full strength.

Outcomes/Evidence in the Literature

Cahill, BR. "Osteolysis of the distal part of the clavicle in male athletes". JBJS Am.
vol. 64. 1982. pp. 1053-8.

(Discusses history of osteolysis of the distal clavicle in weight lifters. 19/21 patients had excellent results after distal clavicle excision. 25 nonoperative patients improved but modified their activity.)

(Outcome study of arthroscopic versus open resection of the distal clavicle. Results were comparable between the groups with a lower morbidity in the arthroscopic distal clavicle excision.)

Summary

Distal clavicle osteolysis can be a debilitating injury to active patients performing repetitive activities. Conservative management including NSAIDS, activity modification and cortisone injections can alleviate the symptoms in the acromioclavicular joint. However, in patients failing conservative management with radiographic evidence of osteolysis, arthroscopic distal clavicle resection through a subacromial approach has a high rate of success in eliminating pain and returning patients to their normal activities.